A new peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) is proposed based on the discrete cosine transform (DCT) and discrete sine transform (DST) precodings. Since the DCT and DST precodings concentrate energy into a few components, the hybrid application of the precodings to the real and imaginary parts of mapping symbols can significantly reduce the PAPR. Simulations show that the proposed scheme achieves significantly low PAPR without degrading the bit error rate (BER) compared to existing precoding schemes.

A partial transmit sequence with a clipping (PTS-Clipping) method can reduce considerably high peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signal. However, exhaustive searching operations are needed in order to find optimal phase factors. Signal distortions also occur because the clipping is a nonlinear operation. In this letter, we propose a new partial transmit sequence (PTS) scheme using a phase factor selection algorithm with preset thresholds. The proposed scheme achieves considerable savings for determining the optimum phase factors without the signal distortions.

Tone reservation (TR) is an efficient peak-to-average power ratio (PAPR) reduction scheme that adds peak reduction tones (PRTs) to the orthogonal frequency division multiplexing (OFDM) signal. However, enormous numbers of iterations are needed to find the optimal PRT set, which makes the TR scheme quite complex. In this letter, we propose a modified TR scheme that considerably reduces the computational complexity of the optimization process for the PRT set compared with the conventional TR scheme.